Process for the dehalogenization of halogeniferous nitrates.



UNITED STATES PATENT OFFICE.

CARL UEBELQor HEIDELBERG, GERMANY.

PROCESS FOR THE DEHALoGENIzATIoN or HALoGENIrERoUs NITRATES.

No Drawing.

To all whom it may concern:

Be it known that I, CARL UEBEL, a resident of Heidelberg, in the Stateof Baden, Germany, have invented certain new and useful Improvements inProcesses for the Dehalogenization of Halogeniferous Nitrates, of whichthe following is a specification.

The naturally occurring nitrates and, especially Chili saltpeter whichis used in large quantities for manurial purposes and in chemicalindustry contain varying amounts, depending on their degree ofpurification, of chloride. chlorates and perchlorates or iodids, iodatesand periodates, together with small quantities of bromin compounds andstages of oxidation thereof; These impurities are extremely deleteriousfor many purposes for which commercial saltpeter is employed, especiallyin the manufacture of nitric acid and they give riseto notinc0nsiderable difficulties and losses in manufacture.

As is well-known the manufacture of nitric acid is generally carriedoutby the distillation of Chili saltpeter with sulfuric acid when thehalogenlcompounds contained in the saltpeter are likewise decomposed andescape partly at the beginning and partly at the end of the operation,giving rise to contamination of the condensed nitric acid with chlorinand iodin, and also rendering difficult the complete condensation of thenitrous gases evolved owing to the formation of nitrosyl compounds. Thusin the manufacture of nitric acid in order to obtain a good yield andpure nitric acid of a high avera e concentration, the so called refinedor doub e refined salt-peter with the lowest possible chlorin content isalmost exclusively employed, since it has been found by experience thatthe percentage yield varies approximately in the same manner as thenitrate content of the saltpeter, so that for example when usingunrefined saltpeter ('9 l95% NaNO the yield of nitric acid is about.

9495% of that required by theory, while when using refined saltpeter(97-98% NaNO the yield is about 98% of that required by theory, whilethe average concentration of the acid produced is essentially higher;obviously it is presupposed that in both the above cases equally goodcondensation apparatus is employed.

When using Chili saltpeter for manurial purposes its contamination bychlorids and iodids is of less importance, but perchlo- Speci fioationof Letters Patent.

Patented Dec. so, 1913.

Application filed December 4, 1912. Serial No. 734,888.

rates are to be feared as plant poisons. The

manufacture of saltpeter-superphosphates when using unrefined saltpeteris an extremely unpleasant operation owing to the chlorin content of thesaltpeter, since the half combined phosphoric acid liberates chlorin andiodin and the mixed manure thus acquires a disagreeable smell, becomesvery hygroscopic and destroys the sacks; moreover in some circumstancesspontaneous ignition may occur owing to the interaction between thesuperphosphates and the halogen compounds of the saltpeter. It is onlydue to these unpleasant properties of the compound manure ofsuperphosphate and unrefined saltpeter that it has hitherto been littleintroduced in agriculture and is unsuitable for export.

Now it has been found that the above halogen compounds which have beenmentioned as injurious impurities of the saltpeter can be removed in asimple manner by heating with a small quantity of sulfuric acid,calculated to be equivalent to the content of halogen compounds or withan equivalent amount of an acid sulfate (bisulfate, polysulfate). Bythese means the saltpeter is technically completely freed from thehalogen compounds, and since according to the present invention thedechlorination is effected at a rather high temperature a dehydration orcalcination of the saltpeter simultaneously occurs, thus rendering it offull value with reference to its nitrate content.

To carry out the process in practice it is not particularly necessaryfor the halogeniferous saltpeter to be intimately mixed with thedechlorinating agent, since if too much of the dechlorinating agent (theactive acid radical of which is capable of liberating nitric acid fromnitrates), is present in one part of the mixture nitric acid will beevolved, which for its part owing to evaporation during thedechlorinating process penetrates to and dechlorinates the particles ofsaltpeter which were not in contact stroyed. For most technical objectssulfuric acid, bisulfate or polysulfate will be the most suitable andrational dechlorinating agents. However, should it be desired to obtainby the dechlorinating process a high percentage saltpeter as free aspossible from contamination by foreign salts such as sulfates, etc.,then nitric acid is the suitabledechlorinating agent. Moreover for thetechand that the moist crystalline meal adhering to the crystalscontains the main quantity of the halogens which thus essentially arisesfrom the adhering mother-liquid.

The process can be carried out in any desired closed mixing andtransport apparatus, heated by steam or directly fired; the apparatusmay be made of cast iron or wrought iron and the mixture, which is to beheated, may be introduced and removed continuously or discontinuously.

For removing and, if desired utilizing the hydrochloric acid, chlorin,bromin and iodin vapors which are evolved possibly with a small quantityof nitrosyl chlorid, which may have been produced by a small excess ofthe dechlorinating agent, the dechlorinating apparatus may be connectedwith a washing, absorption or condensation apparatus.

The temperature necessary for dechlorination may be fixed within widelimits, and may vary from gentle heating to the melt ing point of thesaltpeter. There is a complete decomposition of the halogenids andperchlorates at 100, but the small quantity of iodates contained in thesaltpeter will only be decomposed at temperatures over 100; it issuiiicient for all practical purposes to eifect the dechlorination byheating the apparatus to 100-150 centigrade.

The advantages of the process are at once. clear for the variouspurposes for which saltpeter is employed in industry and agriculture,since when using saltpeter which has been treated according to thepresent invention all the disadvantages are com pletely avoided whichoccur as explained which has not been dechlorinated, thus ca-usingdamage to the workers and the apparatus.

What I claim as newand desire to secure by Letters Patent is r 1. Theprocess for removing halogens from nitrates by mixing the nitrate withan acidic agent capable of decomposing the halogen compounds, the amountof acid being substantially equivalent to the amount of halogen present,without previous dissolving of the nitrate, and heating the mix- I turein order to decompose the halogen compound and to drive off the halogen.

2. The process for removing the halogens from nitrates in which thenitrate is mixed with acidic substances in an -amount substantiallyequivalent to the amount of halogen present, without previousdissolving, and heated to 100150 centigrade.

3. The process for removing the halogens from Chili saltpeter, in whichthe Chili saltpeter is mixed with an acidic substance capable ofdecomposing the halogen compounds in an amount substantially equivalentto the amount of halogen present without previously dissolving thesaltpeter, and

heated to temperatures at which the halogen compounds are decomposed andthe halogen is removed. 7

4. The process of removing 7 from Chili saltpeter in which the Chilisaltpeter is mixed with acidic substances containing the S0 group in anamount substanthe halo-gens tially equivalent to the amount of halogen 7present, without previously dissolving the saltpeter, and heated to100150 centi grade. 7

In testimony whereof I have hereunto set my hand.

CARL UEBEL.

WVitnesses:

FRANZ WVmLovroR, J EAN GRUND.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

